The present invention relates generally to disc drive data storage systems. More particularly, the present invention relates to circuits and methods for reducing parasitic capacitance on a common signal bus to which multiple preamplifiers are connected.
In disc drives and other data storage systems, digital data are written to and read from data storage surfaces. Read and write operations are performed through a transducer which is typically carried on a slider body. The slider and the transducer are sometimes collectively referred to as a head, and typically a single head is associated with each data storage surface. The transducer of a head provides a read back signal, indicative of the data read from the data storage surface, to a preamplifier circuit. After amplification by the preamplifier, the read back signal can be selectively provided to a channel integrated circuit (IC). The channel IC processes the read back signal and provides an output signal which is indicative of the data states of the individual bits in the read back signal data stream, and thereby of data stored on the data storage surface.
The channel IC, also referred to as the read/write channel or simply as the channel, is typically positioned on an electronic circuit card. The preamplifiers are typically connected to the channel using a flexible circuit assembly. A problem frequently occurs when there is more than one preamplifier in the data storage system. The analog read back signals from the preamplifiers are typically tied together to form a common signal bus which is connected to the channel. One common industry practice is to connect the outputs of the preamplifiers together at a location near the preamplifiers such that the flexible circuit assembly serves as the common signal bus. Another practice is to connect the outputs of the preamplifiers together on the electronic circuit card which carries the read/write channel. However, connecting the outputs of the preamplifiers together near the channel adds parasitic capacitance to the common signal bus, which reduces the bandwidth of the total circuit formed by the preamplifiers, signal bus and termination circuitry.
The present invention provides a solution to this and other problems, and offers other advantages over the prior art.
The present invention relates to data storage systems and apparatus, such as disc drive data storage systems, which include multiple preamplifiers coupled through a common signal bus to a signal channel device.
In accordance with one embodiment of the invention, a data storage system and device is provided in which parasitic capacitance between multiple preamplifiers and a signal channel is minimized. Multiple read signals from multiple data heads are amplified by corresponding ones of the multiple preamplifiers. A connection device coupled to each of the multiple preamplifiers selectively electrically couples the amplified read signal from the active preamplifier to the signal channel, while electrically isolating the amplified read signals from the inactive preamplifiers from the signal channel. In addition, a method of coupling multiple preamplifiers to a signal channel is provided.
These and various other features as well as advantages which characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.